Fabricated tubing and the method and apparatus for producing the same



March 15, 1966 E. P. HABDAS 3,240,042 FABRICATED TUBING AND THE METHODAND APPARATUS FOR PRODUCING THE SAME Filed June 11. 1962 INVENTOR.

United States Patent 3,240,042 FABRICATED TUBING AND THE METHOD ANDAPPARATUS FOR PRODUCING THE SAME Edward P. Habdas, Dearborn, Mich,assignor to Calumet & Hecla, Ina, Allen Park, Mich., a corporation ofMichigan Filed lune 11, 1962, Ser. No. 201,515 10 Claims. (Cl. 72-49)The present invention relates to fabricated tubing and the method andapparatus for producing the same.

It is an object of the present invention to provide tubing fabricatedfrom continuous flat strip having its edges turned up to provide asubstantially U-shaped cross section and having its edges tapered toprovide for winding the strip in a helical form to bring sides of theedge flanges into contact and having the abutting sides of said edgeflanges bonded together.

It is a further object of the present invention to provide tubing of thecharacter described in the preceding paragraph in which the inter-bondededge flanges are formed downwardly against the outside diameter of thetubing.

It is a further object of the present invention to provide a method ofmaking tubing which comprises continuously advancing a flat striplongitudinally, forming the edge portions of the strip to extendperpendicular to the plane thereof so as to form a strip of generallyU-shaped cross-section, thereafter rolling or otherwise forming the bentup edge portions or flanges of the strip to a tapered cross-section toaccommodate the strip to coiling to helical formation, thereaftercoiling the strip to bring outside side surfaces of the edge flangesinto abutment, and bonding the edge flanges together to form continuoustubing.

It is a further object of the present invention, as described in thepreceding paragraph, to provide a method in which the strip with itsbent up and tapered edge flanges is coiled on a rotating cylindricalmandrel.

It is a further object of the present invention, as described in eitherof the two preceding paragraphs, to provide a method of forming tubingwhich includes the step of forming the bonded generally radiallyprojecting flange portions inwardly to lie against the outer cylindricalsurface of the tubing.

Other objects and features of the invention will become apparent as thedescription proceeds, especially when taken in conjunction with theaccompanying drawings, illustrating a preferred embodiment of theinvention, wherein:

FIGURE 1 is a more or less diagrammatic view illustrating the method offorming tubing and illustrating the finished tubing in alternativeforms.

FIGURE 2 is a fragmentary section on the line 22, FIGURE 1.

FIGURE 3 is a fragmentary section on the line 33, FIGURE 1.

FIGURE 4 is a fragmentary enlarged section on the line 4-4, FIGURE 1.

FIGURE 5 is a fragmentary enlarged sectional view on the line 5-5,FIGURE 1.

The present invention includes tubing of any convenient size but isparticularly useful in the production of relatively large light-walledtubing such for example as is used in irrigation fields. Tubing of thistype is generally transported manually from place to place and since itis not subjected to any substantial internal pressure, it may berelatively thin-walled.

However, it is necessary for the tubing to be sufliciently stiff so asto permit its transportation without alteration of its generallycylindrical configuration.

As seen in FIGURE 1, such tubing is indicated generally at where it isshown as locate-d on a rotating mandrel 12. The portion of the tubingseen at 10a includes a helical flange, fin or bead 14, the nature andmethod of production of which will subsequently be described. For thepresent however, it is to be noted that this continuous helical flangeconstitutes a stiffening means which renders a substantial length of thetubing self-supporting, at least suificiently so as to permit readytransportation.

If designed, and as a modification of the tubing having theconfiguration illustrated in the zone designated 10a, the tubing mayhave the configuration designated in the zone 10b in which the flange isbent over and flattened against the outer cylindrical surface of thetubing as indicated at 14b.

It will of course be apparent that for maximum stiffness it is preferredto leave the flange 14 extending generally radially outwardly from thetubing as designated in the zone 10a. Where such stiffness is notrequired the flange may be bent down as indicated at 14b.

The method of producing the tubing is apparent from FIGURE 1 in whichcontinuous flat strip 20 is advanced for example from a storage reel,through a forming station designated 21 in which inner forming rolls 22and 24 are carried by a support 26 and cooperate with outer formingrolls 27 and 28 respectively. The advance of the flat stock through theforming station 21 results in forming predetermined edge portions of thestrip upwardly into individual flanges 30 and 32, as best seen in FIG-URE 2. Since the operation carried out at the forming station 21 isessentially a bending operation, it will of course be apparent that thebent up flanges 30 and 32 are of uniform thickness from edge to edge andthat accordingly, the strip 20 as it advances beyond the forming station21 is essentially a flat strip.

At a forming station 34 means are provided for edge thinning or taperingthe edge flanges 30 and 32 to the tapered cross-section illustrated at30a and 32a in FIG- URE 3. This tapering operation is accomplished byedge thinning rolls 35 and 36 operating against a stationary anvil 38.Inasmuch as the edge flanges 30 and 32 are tapered substantiallyuniformly, the tapered flanges may be made to conform to a curvature ofthe intermediate portion of the strip 20 which permits it to be formedaround the cylindrical mandrel 12. In order to carry out this operationmost efficiently, the anvil 38 and the thinning rolls 35 and 36 arelocated as closely as possible to the zone of tan-gency between theadvancing generally flat strip 20 with the cylindrical surface of themandrel 12. Thus, referring to FIGURE 1, it will be observed that therolls 35 and 36 are in alignment with the axis of the mandrel 1-2 andhence, are not located directly opposite each other across the width ofthe advancing strip 20. This arrangement tends to form the strip into ahelical path and its exact position is determined by engagement with therotating mandrel.

In FIGURE 1 the roll 36 operates with the anvil 38 to form the righthand flange 32 into the required tapered form by direct engagement withopposite sides thereof. The roll 35 however, cooperates with the mandrelto engage not only the flange 30 of the advancing stripbut also thefirst convolution of the flange 32 so as to produce the configurationillustrated in FIGURE 4.

Instead of having the roll 35 operate to taper the flange against theanvil 38 as suggested in FIGURE 1, it may operate in advance of the fullline position as for example in the dotted line position designated 35a,in which case it will impart a taper to the flange 30 to the shapeillustrated at 30a, FIGURE 3, prior to engagement of the flange 30a withthe flange 32a of the preceding convolution. Roll 36 is then preferablyoperated in the position 36a.

In addition to edge thinning or tapering the flanges 30 and 32 to theconfiguration illustrated at 30a and 32a, the anvil 38 and the roll 36serve as abutment means insuring continuous advance of the helicallycoiled strip on the rotating mandrel. Since the direction of advance ofthe strip as it engages the surface of the mandrel is different from theinstantaneous direction of the engaged surface of the mandrel, it willof course be apparent that the tube assembly is in effect slidingcontinuously longitudinally on the mandrel.

Means are provided for bonding the confronting surfaces of the taperedflanges 30a and 32a so as to form the helically wound strip into acontinuous sealed tube. This means is illustrated in FIGURE 1 as takingthe form of a pair of welding electrodes 40 and 4-2 shaped to press theflanges 30a and 32a into firm contact and to effect a weld by elevatingthe temperature of the flanges by current passing therethrough from asource diagrammatically indicated at 44. Obviously, the welding actionmay be controlled by the pressure exerted on the flanges by theelectrodes 49 and 42, the angular extent of the electrodes, the weldingcurrent applied to the electrodes, and the rate of advance of the strip20. It will further be understood that the welding operation asillustrated and described herein is merely one convenient method ofeffecting a satisfactory bonding of the strip, assuming that thematerial may be bonded by such an operation.

If desired, the composite double thickness flange 14 produced by weldingflanges 30a and 32a together may be left standing, in which case itserves as an efficient means for stiffening the composite tubing. Itwill of course be appreciated that the stiffening action may be variedby controlling the height of the helical fins and similarly, bycontrolling the thickness of the fins.

In some cases it may be preferred to eliminate the radially outstandinghelically extending fin or flange 14, in which case a flattening roller50 may be provided in position to engage the flange 14 and to flatten itdownwardly against the cylindrical surface of the tubing as shown in thezone In this case the finished tubing at the zone of the bondedconnection between adjacent convolutions will have the appearance shownin FIG- URE 5, where the flange 14b is shown as flattened down againstthe surface of the tubing.

Advance of the strip onto the mandrel may be accomplished by rotatingthe mandrel and drawing the strip through the sets of rolls 22, 24, 27and 28, and 35, 36. However, since the invention finds its mosteflicient operation in the production of relatively thin-walled tubing,it will ordinarily be desirable to effect powered rotation of therollers which form the edges of the strip into U- shaped configurationas well as the edge thinning or tapering rolls. The rolls mayconveniently be driven in such a way that they reduce the tension in thestrip but the actual rate of advance of the strip is determined by thespeed of rotation of the mandrel 12. In other words, power is applied tothe rolls 34, 36 and either 22 and 24 or 27 and 28 so that tension inthe strip intermediate the sets of rolls and intermediate the rolls 35,36 and the mandrel is substantially less than if the strip were to bepulled through the roll devices solely by tension developed from therotating mandrel.

While the present invention is particularly applicable to the productionof 'metal tubing such for example as aluminum or aluminum alloy tubing,it is apparent that it might be applied to the production of plastictubing, in which event elements 40 and 42 instead of being electrodesfor passing welding current through the flanges, would be electricallyheated elements effective to produce a bond in the plastic material bythe application of heat and pressure.

The drawings and the foregoing specification constitute a description ofthe improved fabricated tubing and the method and apparatus forproducing the same in such full, clear, concise and exact terms as toenable any person skilled in the art to practice the invention, thescope of which is indicated by the appended claims.

What I claim as my invention is:

1. Apparatus for producing continuous tubing from flat strip materialwhich comprises a mandrel, means for rotating the mandrel, means foradvancing flat strip material longitudinally in a plane tangent to themandrel and in a direction oblique to the axis of the mandrel, rollmeans for bending the edges of the strip material to form flangesextending in the same direction from the plane of the strip, rolltapering means engageable with the flanges in a zone closely adjacent tothe mandrel to taper the thickness of the flanges outwardly so as toproduce a helical form to the strip to assist in coiling it in helicalconvolutions on the rotating mandrel with the flanges of adjacentconvolutions thereof in abutment, and means engageable with the abuttingtapered flanges of the coiled strip on the mandrel for bonding thecontacting surfaces of the flanges together, the roll tapering meanscomprising an anvil located substantially at the zone of tangencybetween the advancing strip and the surface of the mandrel, a first rollcooperating with an anvil to taper the flange at the edge of the stripremote from the previously formed convolutions to a predetermined tapereffective to coil the tapered flange helically to conform to themandrel, a second roll cooperating with the anvil in a position toengage the previously tapered flange of the preceding convolution andthe adjacent untapered flange of the advancing strip and to taper theadvancing flange of the strip to cause it to coil helically inconformity with the diameter of the rotating mandrel and simultaneouslyto press the tapered flanges of the adjacent convolutions firmlytogether.

2. Apparatus for producing continuous tubing from flat strip materialwhich comprises a mandrel, means for rotating the mandrel, means foradvancing flat strip material longitudinally in a plane tangent to themandrel and in a direction oblique to the axis of the mandrel, rollmeans for bending the edges of the strip material to form flangesextending in the same direction from the plane of the strip, rolltapering means engageable with the flanges in a zone closely adjacent tothe mandrel to taper the thickness of the flanges outwardly so as toproduce a helical form to the strip to assist in coiling it in helicalconvolutions on the rotating mandrel with the flanges of adjacentconvolutions thereof in abutment, and means engageable with the abuttingtapered flanges of the coiled strip on the mandrel for bonding thecontacting surfaces of the flanges together, the roll tapering meanscomprising an anvil located substantially at the zone of tangencybetween the advancing strip and the surface of the mandrel, a first rollcooperating with an anvil to taper the flange at the edge of the stripremote from the previously formed convolutions to a predetermined tapereffective to coil the tapered flange helically to conform to themandrel, a second roll cooperating with the anvil at a point in advanceof the zone of tangency between the advancing strip and the surface ofthe mandrel shaped to taper the thickness of the flange at the edge ofthe advancing strip adjacent previously formed convolutions to a taperedconfiguration designed to coil the tapered flange into conformity withthe diameter of the rotating mandrel.

3. Apparatus for producing continuous tubing which comprises acylindrical mandrel, means for rotating the mandrel in a fixed position,means for advancing a strip comprising a flat web and edge flanges bentto extend in the same direction from the web to form a channel-shapedcross-section substantially tangentially of the mandrel and in adirection oblique to the axis of said mandrel, taper means adjacent thezone of tangency of the web to said mandrel comprising means forapplying pressure progressively longitudinally of said flanges betweenopposite edges thereof, said taper means comprising means locatedwiithin the channel of said advancing strip substantially at the zone oftangency with said mandrel and engaging the inner surfaces of theflanges thereof, means to apply pressure progressively longitudinally tothe outer surfaces of said flanges, and means for bonding the taperedflanges of adjacent convolutions of said strip together.

4. Apparatus as defined in claim 3 in which said last means comprisesone roll engageable directly with the outer surface of the flange at theedge of the strip opposite to the direction of advance of the completedtube.

5. Apparatus as defined in claim 3 in which said last means comprisesone roll engageable directly with the outer surface of the flange at theedge of the strip opposite to the direction of advance of the completedtube, and a second roll engageable with the inner surface of said lastmentioned flange after it has been coiled into engagement with the outersurface of the other flange of said strip at the zone of tangency withsaid mandrel.

6. Apparatus as defined in claim 3 in which said last means comprisesrolls engageable directly with the outer surfaces of both of saidflanges.

7. The method of making fabricated tubing which comprises advancing astrip having a flat central web and edge flanges bent in the samedirection to form a channelshaped cross-section toward a rotatingcylindrical mandrel in a direction substantially tangent to the mandreland at an angle oblique to its axis, substantially at the point oftangency with the mandrel rolling both of the edge flangeslongitudinally of the strip to an outwardly tapered cross-section andsubstantially simultaneously coiling the strip around the mandrel into aclosed tubular configuration with outer surfaces of the tapered flangesin contact, and bonding the surfaces of said flanges together to form acontinuous tube.

8. The method as defined in claim 7 which comprises sliding thecompleted tubing longitudinally on the rotating mandrel as newconvolutions are added by continued advance of the strip.

9. The method as defined in claim 7 in which the step of tapering theflanges comprises advancing each of the flanges between forming devicesincluding rolls having axes disposed substantially perpendicular to theplane of the flat web of the strip.

10. The method as defined in claim 7 in which the step of tapering ofthe flanges comprises applying rolling pressure progressivelylongitudinally of one flange, coiling the strip to bring the taperedflange into side abutment with an untapered flange at the opposite edgeof said strip from said one flange, and tapering said other flange byapplying rolling pressure progressively longitudinally of said flangesto both of said flanges.

References Cited by the Examiner UNITED STATES PATENTS 470,738 3/1892Bayles 138--154 1,263,340 4/1918 Silk 138154 1,840,317 1/1932 Horvath15364.5 1,918,137 7/1933 Scarritt 113--35 2,233,233 2/1941 Williams11335 2,734,471 2/1956 Bornand 11335 2,752,873 7/1956 Freeze 113-352,812,794 11/1957 Chapman 153-645 3,000,084 9/1961 Garland 15364.5

CHARLES W. LANHAM, Primary Examiner.

NEDWIN BERGER, MICHAEL V. BRINDISI,

Examiners.

R. J. HERBST, E. D. OCONNOR, Assistant Examiners.

1. APPARATUS FOR PRODUCING CONTINUOUS TUBING FROM FLAT STRIP MATERIALWHICH COMPRISES A MANDREL, FOR ROTATING THE MANDREL, MEANS FOR ADVANCINGFLAT STRIP MATERIAL LONGITUDINALLY IN A PLANE TANGENT TO THE MANDREL,ROLL MEANS DIRECTION OBLIQUE TO THE AXIS OF THE MANDREL, ROLL MEANS FORBENDING THE EDGES OF THE STRIP MATERIAL TO FORM FLANGES EXTENDING IN THESAME DIRECTION FROM THE PLNE OF THE STRIP, ROLL TAPERING MEANSENGAGEABLE WITH THE FLANGES IN A ZONE CLOSELY ADJACENT TO THE MANDREL TOTAPER THE THICKNESS OF THE FLANGES OUTWARDLY SO AS TO PRODUCE A HELICALFORM TO THE STRIP TO ASSIST IN COILING IT IN HELICAL CONVOLUTIONS ON THEROTATING MANDREL WITH THE FLANGES OF ADJACENT CONVOLUTIONS THEREOF INABUTMENT, AND MEANS ENGAGEABLE WITH THE ABUTTING TAPERED FLANGES OF THECOILED STRIP ON THE MANDREL FOR BONDING THE CONTACTING SURFACES OF THEFLANGES TOGETHER, THE ROLL TAPERING MEANS COMPRISING AN ANVIL LOCATEDSUBSTANTIALLY AT THE ZONE OF TANGENCY BETWEEN THE ADVANCING STRIP ANDTHE SURFACE OF THE MANDREL, A FIRST ROLL COOPERATING WITH AN ANVIL TOTAPER THE FLANGE AT THE EDGE OF THE STRIP REMOTE FROM THE PREVIOUSLYFORMED CONVOLUTIONS TO A PREDETERMINED TAPER EFFECTIVE TO COIL THETAPERED FLANGE HELICALLY TO CONFORM TO THE MANDREL, A SECOND ROLLCOOPERATING WITH THE ANVIL IN A POSITION TO ENGAGE THE PREVIOUSLYTAPERED FLANGE OF THE PRECEDING CONVOLUTION AND THE ADJACENT UNTAPEREDFLANGE OF THE ADVANCING STRIP AND THE TAPER THE ADVANCING FLANGE OF THESTRIP OF CAUSE IT TO COIL HELICALLY IN CONFORMITY WITH THE DIAMETER OFTHE ROTATING MANDREL AND SIMULTANEOUSLY TO PRESS THE TAPERED FLANGES OFTHE ADJACENT CONVOLUTIONS FIRMLY TOGETHER.